1. Field of the Invention
The present invention relates to a tape member for holding semiconductor devices of a surface mount type at intervals in the lengthwise direction of the tape member.
2. Description of the Related Art
Usually, ICs of a surface mount type are shipped from a factory to the user in large quantities. In some cases, hundreds of ICs to tens of thousands of ICs are transported to the user. To protect the ICs during transportation, they are wrapped up with a tape member while being spaced from one another.
An example of a tape member is shown in FIGS. 3A, 3B and 3C. As is shown, the tape member comprises about 300 .mu.m-thick carrier tape 1 which is formed of an organic material, such as vinyl chloride resin or polyimide, and has a plurality of depressed sections arranged in the lengthwise direction thereof; and seal tape 2 which is formed of the same organic material as carrier tape 1 and has a thickness of about 50 to 100 .mu.m. After being manufactured in the factory, the ICs are tested to eliminate defective ones, and only those ICs which have passed the check are inserted into the respective depressed sections of the tape member one by one. After the ICs are inserted into the depressed sections, the depressed sections are covered with seal tape 2 and are then sealed by thermocompression bonding. Before being transported to the user, the sealed ICs are subjected to a durability and moisture resistance test. In this test, the ICs are left for about 20 hours in an environment whose temperature is 85.degree. C. and whose humidity is, for example, 85%, to thereby detect whether or not the resin portions and the semiconductor chips of the ICs crack. If test is OK, the tape member, in which the ICs are sealed, is wound around reel 6. It should be noted that the tape member formed of the above organic material does not have satisfactory thermal resistance, moisture resistance or radiation resistance. Therefore, the tape member is sealed within an aluminum case after it is wound around reel 6. In this condition, the ICs are transported to the user.
As mentioned above, the tape member does not have satisfactory thermal resistance, moisture resistance or radiation resistance, and is therefore sealed in an aluminum case. Even if the user needs only several ICs, he or she has to open the aluminum case, with the result that all ICs sealed in the aluminum case are exposed to both radiation and moisture. Therefore, it is likely that the ICs will be adversely affected by radiation. It is also likely that the ICs will absorb moisture of the atmosphere, in addition to the moisture absorbed therein at the time of the moisture resistance test. If an excessive amount of moisture is contained in the ICs, it will evaporate when the ICs are mounted on a board by soldering, thus adversely affecting the internal structure of the ICs. In addition, the resin portions of the ICs may crack, or bonding pads (formed of aluminum or the like) may corrode, resulting in electrical disconnection. Where ICs are exported to transport them to a user in a foreign country, the case containing the ICs has to be opened at the customs. If the case is opened, the ICs in the case will be exposed to radiation or moisture before they are delivered to the user. It should be also noted that the tape member formed of an organic material does not have a sufficient mechanical strength, and should be therefore handled carefully during transportation.
To solve the above problems, a packing operation is required on the part of the user. This packing operation is very troublesome for the user since the ICs have to be left for 20 hours at a temperature of about 150.degree. C., or for 48 hours at a temperature of about 70.degree. C. Further, there is a growing tendency to employ thinner IC envelopes, so as to enable ICs to be mounted on a board at a high density. Under the circumstances, the development of tape members free from resin cracks or semiconductor chip cracks has been demanded in the art.